ISSN:
1089-7623
Source:
AIP Digital Archive
Topics:
Physics
,
Electrical Engineering, Measurement and Control Technology
Notes:
An experimental study on the production of negative ions at a pure barium surface mounted in a multicusp bucket source is presented. The conversion efficiency, i.e., the ratio of the extracted negative-ion current and the positive-ion current incident on the surface, for deuterium and for hydrogen, have been measured as a function of source pressure, converter bias, and distance between conversion surface and extraction aperture. The conversion efficiency for deuterium is somewhat larger when compared to hydrogen. The conversion efficiencies obtained agree with a model, taking into account the concentration of hydrogen in the barium surface layers. The cross sections which were measured for the stripping of negative ions by neutral gas agreed well with values from literature. The experimentally determined divergence of the surface-produced beam was 4.5° for hydrogen and 3.6° for deuterium at an energy of 100 eV. At a source pressure of 5 mTorr, the volume-produced negative-ion current could be enhanced by 10%; for 1 mTorr this enhancement was of the order of 25%.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1140360
